gitlab-ci: Build wlroots

Build it once with and without xwayland so we're sure both work

.gitlab-ci.yml

+variables:
+  DEPS: debhelper libcap-dev libdrm-dev libegl1-mesa-dev libgbm-dev
+        libgles2-mesa-dev libinput-dev libpixman-1-dev libsystemd-dev
+        libwayland-dev libxcb1-dev libxcb-composite0-dev libxcb-icccm4-dev
+        libxcb-image0-dev libxcb-render0-dev libxcb-xfixes0-dev
+        libxkbcommon-dev meson pkg-config wayland-protocols
+        build-essential
+
+before_script:
+ - apt-get -y update
+ - apt-get -y install $DEPS
+
+build-with-xwayland:
+  stage: build
+  tags:
+    - librem5
+  script:
+    - export LC_ALL=C.UTF-8
+    - meson . _build -Denable-xwayland=true
+    - ninja -C _build
+    - ninja -C _build install
+
+build-without-xwayland:
+  stage: build
+  tags:
+    - librem5
+  script:
+    - export LC_ALL=C.UTF-8
+    - meson . _build -Denable-xwayland=false
+    - ninja -C _build
+    - ninja -C _build install
+